In December Microsoft switched off their aging Microsoft Volume Licensing Site (MVLS) and transitioned users to its new Volume Licensing Service Center (VLSC). The switchover had been planned for some time but was immediately hit with issues, such as customers being unable to login and being unable to access their agreements. The site was eventually taken offline while maintenance was undertaken.

The new site, which allows Microsoft customers with a volume licensing agreement to download software, access product keys and take advantage of benefits such as training vouchers and planning services, is relied upon by thousands of organisations.

Despite Microsoft's planning and its scheduled downtime, during which the errors were supposedly addressed, customers have continued to complain about the site's unavailability with some customers reportedly unable to access their volume license details at all since the transition began on December 14.

The Register is now reporting that it has been contacted by one of its readers who, upon registering with the VLSC and entering his own agreement details, was presented with the names, e-mail addresses and subscription details of many other customers. The reader has also provided screenshots to support his claims that the site is inadvertently leaking customer details.

Microsoft has apologised to customers for the recent problems with the VLSC and are continuing to remedy any remaining issues although they have yet to comment on The Register's claims.